i just want to explain somethings

The trick here lies in the purely physical things, Number one the gravity!
Number two and the most important point is the position of the two pensThe status of the pen above the other Pen and in opposite direction
it's impossible to be static
it must move in any direction
Because of the extreme gravity that affect on the pen confluence point

This is from my point of view
and i'm sure 100%
that i'm right